A common procedure for handling pain associated with degenerative spinal disk disease is the use of devices for fusing together two or more adjacent vertebral bodies. The procedure is known by a number of terms, one of which is vertebral interbody fusion. Interbody fusion can be accomplished through the use of a number of devices and methods known in the art. These include screw arrangements, solid bone implant methodologies, and fusion devices which include a cage or other mechanism which is packed with bone and/or bone growth inducing substances. All of the above are implanted between adjacent vertebral bodies in order to fuse the vertebral bodies together, alleviating associated pain.
There are a number of drawbacks to undergoing interbody fusion. One drawback is that interbody fusion at one or more levels of the spine may cause decreased motion of the spine. Another drawback is that having interbody fusion at one or more levels of the spine may cause more stress to be transferred to adjacent levels. Transferred stress may cause new problems to develop at other levels of the spine, which may lead to additional back surgery.
Alternatives to interbody fusion surgery have been proposed including the use of artificial spinal disks. Such artificial spinal disks act like cushions or “shock absorbers” between vertebrae and may contribute to the flexibility and motion of the spinal column. Thus a purpose and advantage of such artificial spinal disks is to replace a degenerated spinal disk, while preserving the range of motion of the spine. Replacement of a spinal disk with an artificial disk may treat underlying back pain, while protecting patients from developing problems at an adjacent level of the spine.
A number of different artificial disks have been proposed. For example, one such proposal includes an artificial disk primarily comprising two metal metallic plates between which is a core that allows for motion. Another proposal includes two spinal disk halves connected at a pivot point. Other artificial disks have been proposed in the art.